Find Force M Exerted by Muscle in Test Apparatus

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To find the force M exerted by the flexor muscle on the forearm, the torque generated by the horizontal force F must be balanced by the torque produced by the muscle force M. The torque due to the horizontal force is calculated as 59.52 Nm using the lever arm length of 0.31 m. To solve for M, the torque at the muscle's point of application, which is 0.047 m from the elbow, must also be considered. The sum of the moments about the elbow joint should equal zero, allowing for an equation that sets the torques equal to each other. This approach will yield the magnitude and direction of the muscle force M.
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A person exerts a horizontal force |F| = 192 N in the test apparatus shown in the drawing. Find the horizontal force M (magnitude and direction) that is flexor muscle exerts on his forearm. (L = 0.31 m, h = 0.047 m)

http://img238.imageshack.us/img238/1465/c9p17iy6.jpg

I know that the torque for the .31m length is equal to 59.52 Nm; how do I begin to solve the force M for the second length of .047m?
 
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The sum of the moments about the elbow joint must = 0.
 
does this mean I can calculate the torque for both points and add them in an equation and set them equal to 0?
 
Thread 'Correct statement about size of wire to produce larger extension'

Thread 'Correct statement about size of wire to produce larger extension'

The answer is (B) but I don't really understand why. Based on formula of Young Modulus: $$x=\frac{FL}{AE}$$ The second wire made of the same material so it means they have same Young Modulus. Larger extension means larger value of ##x## so to get larger value of ##x## we can increase ##F## and ##L## and decrease ##A## I am not sure whether there is change in ##F## for first and second wire so I will just assume ##F## does not change. It leaves (B) and (C) as possible options so why is (C)...
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